Prognostic Value of the Preoperative Tumor-to-Blood Pool Standardized Uptake Value Ratio Derived from FDG-PET/CT in Distal Bile Duct and Ampullary Cancers.

PURPOSE:This study investigated the prognostic value of the preoperative tumor-to-blood pool standardized uptake value ratio (TBR) on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in patients undergoing pancreatoduodenectomy (PD) for distal bile duct and ampullary cancers. METHODS:We retrospectively reviewed 100 patients who underwent PD between January 2011 and December 2024. TBR was calculated as tumor SUVmax divided by the SUV of the descending aorta. The optimal cutoff for overall survival (OS) was determined using time-dependent ROC curve analysis. Survival outcomes were evaluated using Kaplan-Meier and multivariable Cox regression analyses. RESULTS:A TBR cutoff of 2.30 was identified. Patients with high TBR (≥ 2.30) had significantly higher preoperative bilirubin, C-reactive protein, and CA19-9 levels, more frequent lymph node metastasis, poorer differentiation, and longer operation time than those with low TBR. High TBR was associated with worse OS and recurrence-free survival (RFS) (both p < 0.001). Multivariate Cox regression confirmed high TBR as an independent predictor of poor OS (Hazard Ratio: 2.88, p = 0.044). CONCLUSIONS:Preoperative TBR on FDG-PET/CT was associated with adverse pathological features and inferior survival in patients undergoing PD for distal bile duct and ampullary cancers. These findings suggest that TBR may be useful as an adjunctive PET-derived marker for preoperative risk stratification.